1. Field of the Invention
This invention relates to continuous pressure cooking apparatus for use in feeding, conveying and/or discharging food material. In particular, the present invention relates to a sealing and discharging assembly between the pressure screw feeder assembly and the continuous pressure cooker assembly in the cooking apparatus.
2. Description of the Prior Art
The present invention is an improvement over apparatuses which are disclosed in U.S. Pat. Nos. 3,246,594 and 4,179,043, the contents of which are incorporated herein by reference.
Briefly, in the aforesaid U.S. Pat. No. 3,246,594 there is disclosed an apparatus for continuously pressure cooking various cereal materials under superatmospheric steam conditions to produce a cooked, extrudable mash and, then, extruding the cooked mash through a plurality of die orifices. An important requisite for the successful operation of this apparatus is the ability to form a pressure resistant seal at the inlet to the pressure cooker. In accordance with the patent, this seal is created by compacting the dry incoming material or particulate product mix into a pressure resistant plug in the outlet terminal end of its pressure feeder mechanism. Further, in accordance with the patent, after the seal has been formed, it is generally then desirable or necessary to abrade the compacted material back to its original particulate state to assure uniform and thorough penetration of the superatmospheric steam in the pressure cooker. A suitable mechanism and procedure for accomplishing this sealing and abrading function is disclosed in the patent.
More specifically, in accordance with the above-mentioned patent, dry incoming material is advanced from a materials inlet or hopper to the pressure cooker inlet by a pressure feeder mechanism consisting of a screw conveyor. As the material advances from the inlet of the screw conveyor to its discharge or terminal end, partial compaction of the material occurs as a result of a decrease in the flight channel depth of the feeder screw, created by increasing the root diameter of the screw. Further compaction occurs as the material advances against a rotatable and axially translatable seal plate or gate disposed in confronting relation to the outlet end of the screw conveyor. The seal plate or gate is mounted on a shaft extending through or into a feeder housing connecting the screw conveyor discharge to the pressure cooker inlet. The force with which the seal plate is held against the advancing material, as well as its axial movement, is controlled by a fluid actuated, piston-cylinder assembly connected to the distal end of the seal plate shaft. The abrasion function is accomplished by rotating the seal plate shaft and, accordingly, the seal plate and associated abrading lugs through a jack-shaft/gear drive arrangement. During normal operation, simultaneous axial movement and rotation of the seal plate shaft will continuously take place.
U.S. Pat. No. 4,285,271 provides a seal plate drive assembly comprised of a rotatable and axially translatable seal plate shaft that supports the seal plate in the feeder housing or feeder discharge housing and is telescopically received by a tubular drive shaft mounted in a pair of anti-friction bearings externally of the feeder housing and, wherein, a spline coupling preferably interconnects the two shafts to permit co-rotation while allowing axial translation of the seal plate shaft. Drive means are provided to drive the tubular drive shaft in rotation and to impart axial translation to the seal plate shaft. Also, a first seal means is disposed between the seal plate shaft and the tubular drive shaft at a location adjacent the feeder housing to prevent ingress of product mix and superatmospheric steam between the shafts and a second seal means is cooperatively associated with the feeder housing and the tubular drive shaft to prevent egress of product mix and superatmospheric steam from the feeder housing and along the outer periphery of the tubular drive shaft.